Since an HNB (Home Node B) forming the above femtocell system is installed in an ordinary household and an office, a usage rate of the HNB and an HNB-GW is low depending on the time of day. Although there are various research for a method of operating the HNB with reduced electric power, research is still required for a method of operating the HNB-GW with reduced electric power.
The femtocell system related to the present invention includes the HNB, the HNB-GW, and an HMS (Home Node B Management System). The HNB is a small-scale base station installed in homes and offices, and is also referred to as an FAP (Femto Access Point). The HNB-GW is a device that relays signals between a switching center and the HNB.
The HMS (Home Node B Management System) is equipped with a function for managing configuration information of the HNB such as a list of HNB-GWs capable of accepting HNB Registration from the HNB.
In regard to the above operation of HNB-GW with reduced electric power, there are techniques (e.g. patent literatures 1 and 2) for transitioning to a power saving state or an operating state depending on a server load and an accommodating status of mobile terminals. The technique disclosed in patent literature 1 deletes an entry from an MME pool held to an eNodeB before MME (MME) transitions to a power saving mode.
Note that a UE (User Equipment) Registration number is used as an index representing the usage rate of HNB-GW that is used in the method of operating the HNB-GW with reduced electric power. The UE Registration is a standard operation defined in following non patent literature 1.
In order for the HNB-GW to obtain or change a list of HNB-GWs capable of accepting the HNB Registration from the HNB, the HMS (Home Node B Management System) transmits to the HNB “RPC:Get Parameter Values” or “RPC:Set Parameter Values”, and the HMS notifies the HNB-GW of the result.
Transmitting “RPC:Get Parameter Values” and “RPC:Set Parameter Values” from the HMS to the HNB is a standard operation defined in non patent literature 2.
The HNB is equipped with a function to hold a “list of HNB-GWs capable of accepting the HNB Registration from the corresponding HNB”. Generally, as described in “FAPGWServer1”, “FAPGWServer2”, and “FAPGWServer3” in following non patent literature 3, multiple HNB-GWs can be specified to the “list of HNB-GWs”.